The difficulties of gaining intravenous access such as for drawing blood, intravenous fusion, etc., are well known to vary from one patient to another. Some patients have very prominent veins and this situation simplifies the procedure although, even for some of these patients, their veins have a tough resiliency that makes the veins difficult to penetrate with a hypodermic needle. In the context of this specification, the term, hypodermic needle, will be understood to mean any access device such as a syringe with needle for drawing blood, intravenous catheter, etc. In other patients, the veins are small, deepest, and scarcely visible so that gaining intravenous access is very unpleasant for both the practitioner and the patient. The complexion of the patient can be another troublesome factor. For example, the veins of Afro-Americans are not nearly as visible as the veins of many other patients which hinders the process of finding a vein and drawing blood therefrom. Infants have immature vascular development. Obese patients have venous structure that is difficult to penetrate. At the very least, these complications can greatly increase the stress experienced by the patient. At worst, delays in gaining intravenous access can result in death.
U.S. Pat. No. 4,817,612 to Pennypacker et al discloses an arrangement shown in FIGS. 1 and 2 (prior art) for locating vascular structures V including a conventional video display D having a monitor screen M, viewed by the eye of an observer through a lens system 14. A mirror 16 deflects an image through filter F to camera C which includes a charged coupled device 20 with lens system 22. A problem with the arrangement of FIGS. 1 and 2 is that the device must be supported by placing the bottom edge of the mirror 16 against the surface of the limb of the patient. This is not an acceptable practice for many situations. A second problem is that placement of the mirror 16 in the vicinity of the patient interferes with applying the hypodermic needle to the required location on the patient. A third consideration is a limited range of location for placement of the light L of the Pennypacker system. A fourth consideration is the requirement that the patient remain motionless for an extended period of time in one location which is a difficult requirement for small children. A fifth consideration is that the cost of the Pennypacker device, including the half silvered mirror and optical system for reflecting an image of the area of interest onto the camera is greater than the cost of the present invention.
U.S. Pat. No. 5,519,208 to Esparza et al discloses a lamp means radiating an area of the body and a mirror for reflecting only wavelengths selected to enhance the venous image of the area so that an operator is guided to that area of the skin.
U.S. Pat. No. 5,608,210 to Esparza et al discloses a head set containing a CCD camera (charge coupled device)
All of these devices rely on the discovery that the veins and arteries absorb infrared light more strongly than areas of the skin that do not contain veins. Use of these devices is characterized by the following problems:
1. The darker the skin, especially with Afro-Americans, the less is the contrast of venous areas compared to nonvenous areas when viewed with these devices of the prior art. This makes it difficult to see any but the most prominent veins in many patients. PA1 2. The arrangement of the equipment, i.e., camera, mirrors, lens stands, etc., mitigates the convenience necessary for performing an efficient operation. PA1 3. The presence of these paraphenalia is intimidating to the patient, especially a child, and adds to his discomfort of the whole procedure. PA1 a CCD camera; PA1 a filter mounted on the camera that blocks out light in the predominantly visible wave length range and transmits light having a wavelength in the ultraviolet and infrared wavelength range; PA1 a source of light which emits light in the infrared range, the visible wavelength range and the ultraviolet wavelength range.